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2020 Fiscal Year Annual Research Report

Search for sterile neutrinos through precision measurements of tau lepton decays

Research Project

Project/Area Number 16H02175
Research InstitutionThe University of Tokyo

Principal Investigator

相原 博昭  東京大学, 大学院理学系研究科(理学部), 教授 (60167773)

Project Period (FY) 2016-04-01 – 2021-03-31
Keywords素粒子実験 / Bファクトリー / タウレプトン / ニュートリノ
Outline of Annual Research Achievements

素粒子物理学の標準理論を超える理論として有力視されているモデルの一つに、標準理論のゲージグループ下ではチャージを持たないフェルミオン、ステライルニュートリノを導入するモデルがある。本研究では、KEKBファクトリーで得られたビッグデータを使ったタウレプトン崩壊の精密測定によって、ステライルニュートリノの探索を行っている。標準理論では、電弱カレントのLorentz structureは V-A 型をとる。レプトン崩壊のパラメータであるMichelパラメータを測定し、標準模型の期待値と比較することで、V-A 型以外の結合を持つ新物理の寄与を探索することができる。特に、τ- → π-e+e-(およびmu+mu-)ντという稀崩壊の崩壊幅は、ステライルニュートリノの存在によって、標準理論の期待値を上回る可能性がある。2019年(令和元年)には、Belle実験で得られた約9億のタウ・反タウ対を含むビッグデータを用いて、データの解析を進め、この解析を完了し、博士論文及び査読付き学術雑誌に出版した。その後、この解析を応用して、標準理論では起こらない(レプトンフレーバー保存を破る)τ- → π-e+mu-(およびmu+e-)ντ反応の探索を進めている。

Research Progress Status

令和2年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和2年度が最終年度であるため、記入しない。

  • Research Products

    (21 results)

All 2021 2020 Other

All Int'l Joint Research (2 results) Journal Article (19 results) (of which Int'l Joint Research: 19 results,  Peer Reviewed: 19 results,  Open Access: 19 results)

  • [Int'l Joint Research] Budker Institute of Nuclear Physics(ロシア連邦)

    • Country Name
      RUSSIA FEDERATION
    • Counterpart Institution
      Budker Institute of Nuclear Physics
  • [Int'l Joint Research] University of Ljubljana(スロベニア)

    • Country Name
      SLOVENIA
    • Counterpart Institution
      University of Ljubljana
  • [Journal Article] Measurement of time-dependent C P violation parameters in B 0 → K 0 S K 0 S K 0 S decays at Belle2021

    • Author(s)
      Kang K.H.、Park H.、Higuchi T.、Miyabayashi K.、Sumisawa K.、Adachi I.、Ahn J.K.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 103 Pages: 032003

    • DOI

      10.1103/PhysRevD.103.032003

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Measurement of branching fractions of Λ + c → η Λ π + , η Σ 0 π + , Λ ( 1670 ) π + , and η Σ ( 1385 ) +2021

    • Author(s)
      Lee J.Y.、Tanida K.、Kato Y.、Kim S.K.、Yang S.B.、Adachi I.、Ahn J.K.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 103 Pages: 052005

    • DOI

      10.1103/PhysRevD.103.052005

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Evidence for X ( 3872 ) → J / ψ π + π - Produced in Single-Tag Two-Photon Interactions2021

    • Author(s)
      Teramoto Y.、Uehara S.、Masuda M.、Adachi I.、Aihara H. et al.
    • Journal Title

      Physical Review Letters

      Volume: 126 Pages: 122001

    • DOI

      10.1103/PhysRevLett.126.122001

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Search for the dark photon in B0 → A′A′, A′ → e+e-, μ+μ-, and π+π- decays at Belle2021

    • Author(s)
      The BELLE collaboration、Park S.-H.、Kwon Y.-J.、Adachi I.、Aihara H. et al.
    • Journal Title

      Journal of High Energy Physics

      Volume: 2021 Pages: 191

    • DOI

      10.1007/JHEP04(2021)191

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Measurement of the resonant and nonresonant branching ratios in Ξ 0 c → Ξ 0 K + K -2021

    • Author(s)
      McNeil J.T.、Yelton J.、Bennett J.、Adachi I.、Adamczyk K.、Ahn J.K.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 103 Pages: 112002

    • DOI

      10.1103/PhysRevD.103.112002

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] First determination of the spin and parity of the charmed-strange baryon Ξ c ( 2970 ) +2021

    • Author(s)
      Moon T.J.、Tanida K.、Kato Y.、Kim S.K.、Adachi I.、Ahn J.K.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 103 Pages: 111101

    • DOI

      10.1103/PhysRevD.103.L111101

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Measurement of the branching fraction of the decay B+ → π + π -l+ νl in fully reconstructed events at Belle2021

    • Author(s)
      Bareno C.、Frey A.、Adachi I.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 103 Pages: 112001

    • DOI

      10.1103/PhysRevD.103.112001

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] First search for the ηc2(1D) in B decays at Belle2020

    • Author(s)
      The Belle collaboration、Adachi I.、Aihara H. et al.
    • Journal Title

      Journal of High Energy Physics

      Volume: 2020 Pages: 034

    • DOI

      10.1007/JHEP05(2020)034

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Evidence for a vector charmoniumlike state in e + e - → Ds+ D s2 (2573) - + c.c.2020

    • Author(s)
      Jia S.、Shen C.P.、Adachi I.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 101 Pages: 091101

    • DOI

      10.1103/PhysRevD.101.091101

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Update of inclusive cross sections of single and pairs of identified light charged hadrons2020

    • Author(s)
      Seidl R.、Adachi I.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 101 Pages: 092004

    • DOI

      10.1103/PhysRevD.101.092004

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Search for B0 decays to invisible final states ( + γ) at Belle2020

    • Author(s)
      Ku Y.、Chang P.、Adachi I.、Adamczyk K.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 102 Pages: 012003

    • DOI

      10.1103/PhysRevD.102.012003

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Dalitz analysis of D0 → K- π + η decays at Belle2020

    • Author(s)
      Chen Y.Q.、Li L.K.、Yan W.B.、Adachi I.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 102 Pages: 012002

    • DOI

      10.1103/PhysRevD.102.012002

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Performance of the Belle II Silicon Vertex Detector2020

    • Author(s)
      Tanigawa H.、Adamczyk K.、Aihara H. et al.
    • Journal Title

      Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

      Volume: 972 Pages: 164129

    • DOI

      10.1016/j.nima.2020.164129

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Study of electromagnetic decays of orbitally excited Ξ baryons2020

    • Author(s)
      Yelton J.、Adachi I.、Ahn J.K.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 102 Pages: 071103

    • DOI

      10.1103/PhysRevD.102.071103

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Search for Axionlike Particles Produced in e + e - Collisions at Belle II2020

    • Author(s)
      Abudinen F.、Adachi I.、Aihara H. et al.
    • Journal Title

      Physical Review Letters

      Volume: 125 Pages: 161806

    • DOI

      10.1103/PhysRevLett.125.161806

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Search for a doubly charged D D K bound state in Υ ( 1S, 2S) inclusive decays and via direct production in e + e - collisions at √ s = 10.520 , 10.580, and 10.867 GeV2020

    • Author(s)
      Li Y.、Jia S.、Shen C.P.、Adachi I.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 102 Pages: 112001

    • DOI

      10.1103/PhysRevD.102.112001

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Search for transitions from Υ ( 4 S ) and Υ ( 5 S ) to η b ( 1 S ) and η b ( 2 S ) with emission of an ω meson2020

    • Author(s)
      Oskin P.、Mizuk R.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 102 Pages: 092011

    • DOI

      10.1103/PhysRevD.102.092011

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Search for lepton-number- and baryon-number-violating tau decays at Belle2020

    • Author(s)
      Sahoo D.、Mohanty G.B.、Trabelsi K.、Adachi I.、Adamczyk K.、Aihara H. et al.
    • Journal Title

      Physical Review D

      Volume: 102 Pages: 000010

    • DOI

      10.1103/PhysRevD.102.111101

    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Beam background study for the Belle II Silicon Vertex Detector2020

    • Author(s)
      Tanigawa H.、Adamczyk K.、Aihara H. et al.
    • Journal Title

      Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

      Volume: 982 Pages: 164580

    • DOI

      10.1016/j.nima.2020.164580

    • Peer Reviewed / Open Access / Int'l Joint Research

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Published: 2023-12-25  

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